1. Field of the Invention
This invention relates generally to the field of fuel storage tanks and more particularly to an improved method for cleaning the interior of a fuel storage tank.
2. Description of the Related Art
Fuel storage tanks (herein also referred to as “fuel tanks” or “storage tanks”) are large cylindrical vessels that are commonly maintained at automobile filling stations for storing quantities of fuel, such as gasoline, diesel, and kerosene. Fuel tanks are typically installed several feet underground in a generally horizontal orientation, although above-ground fuel storage tanks are not uncommon.
Over time, water and other liquid and solid fuel contaminants settle and accumulate on the interior surfaces of a fuel storage tank. Fuel tanks must therefore be cleaned on a periodic basis to preserve the quality of the fuel that is stored inside of them. Traditionally, fuel tank cleaning has been accomplished by a process known as kidney loop filtration. This process generally involves pumping stored fuel out of a fuel tank, processing the fuel through a series of filters to remove water and other contaminants from the fuel, and then pumping the filtered fuel back into the fuel tank. This process is repeated in a closed-loop manner with the fuel constantly being cycled from the fuel tank, through filters, and back into the fuel tank until it is determined that the fuel is sufficiently free of contaminants.
A problem that is commonly associated with kidney loop filtration is that the wash force generated by the fuel that is circulated through a fuel storage tank during the cleaning process is often insufficient to loosen heavier contaminants that tend to adhere to the bottom, side, and, to a lesser extent, upper surfaces of the interior of the fuel tank. A layer of heavy contaminants therefore continues to accumulate within the fuel tank unabated through successive cleanings. Stored fuel is thus constantly exposed to the growing layer of contaminants, which results in higher and faster-accumulating levels of contamination in the stored fuel than would normally be present in fuel having no such continuous contaminant exposure.
It is therefore desirable to have an efficient method for effectively cleaning contaminants from the interior of a fuel storage tank, including those heavy contaminants that adhere to a fuel tank's various interior surfaces and tend to resist traditional cleaning methods such as kidney loop filtration.